1. Technical Field
This invention relates generally to document reproduction apparatus and more particularly, to networks of such apparatus wherein one or more front end image data generating devices are networked with one or more output devices or marking engines.
2. Background Art
In the prior art, reproduction apparatus such as electrophotographic copiers, are known that have a scanner for scanning a document to be reproduced and a marking engine for printing copiers of such document. Where such copiers are to be used in a secure environment, it is desirable to ensure that copies of secure originals not be available to unauthorized individuals. Where the copier is an optical copier, images are flash-exposed onto a photoconductor, developed and transferred to copy sheets. Security for optical copiers involves accessibility to the output copies and cleaning of the photoconductor. Both of these can be controlled without difficulty. Currently, some copiers are being manufactured as electronic copiers. Electronic copiers feature an advantage of providing collated copy sets without multiple scanning of each sheet of a multisheet document set original. With electronic copiers, a multisheet document has its individual sheets electronically scanned seriatim and the image data thereon stored in memory. Plural collated copy sets are realized by reading the data plural times front memory to an electronic writer such as a laser or LED recorder. In considering security of the information that is being copied, it is not enough to consider only control of the output copies and the image on the photoconductor. The information in the memory still retains the secure data. Typically, during a series of production jobs and after jobs are printed, the memory could either be erased before inputting new jobs or new jobs can be written into memory over the secure job; see in this regard U.S. Pat. No. 4,894,805. However, a problem does occur where there is an interruption in say a secure copying job. This interruption could occur for a number of reasons including a paper jam or other type of error condition, pressing the &lt;STOP-RESET&gt; button while the machine is running, making a proof copy, pausing for a key sheet or after a job interrupt mode. If the person authorized to make the copies leaves the machine unattended but removes the originals and copies so far made, the machine is still capable of being placed back into its copying mode for producing copies from memory. In order to block unauthorized access to copies, it is known to provide a security feature to a machine that in the event of a stoppage during a production job, a stoppage for only a predetermined period is tolerated. In response to a signal indicating expiration of the period, a cancel job request is sent to the marking engine and all the data in memory is erased by removing power thereto. The operator control panel is then reset as it would be in a typical power up condition and power is restored to the memory.
A problem with removing power to the memory is that other jobs may also be queued in memory and they are lost as well. This is particularly a problem where multiple front end devices such as scanners, raster image processors, fax or others are connected with one or more marking engines using a suitable network facility.